An improved method to approximate closest saddle node bifurcation based on multiple load flow solutions: A new method of voltage stability monitoring and control

Abstract

Although a closest bifurcation point (CBP) is known to be a superior security measure against voltage collapse, no fast computation methods exist presently. In such a circumstance, the authors proposed an approximation method for CBP in Ref. 11 where two major problems were left unsolved: (1) the method cannot take into Q limits of generators and (2) it utilizes a low-voltage power flow solution, which is not easily obtained unless a suitable initial estimate is available. This paper presents a series of techniques to solve these problems. It is shown that the proposed method can provide fairly accurate CBP without suffering any major problems. The total computation time is not more than that of ten power flows even when no information of low-voltage solution is available in advance. The proposed method will make possible a reliable on-line monitoring and control of voltage stability. © 2000 Scripta Technica, Electr Eng Jpn, 133(1): 19–30, 2000